Incubator



F. BABA.

INCUBATOR.

APPLICAHON FILED MAY 13. 1919.

1,41 3,887. Patented Apr. 25, 1922.

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m) atmmeq F. BABA.

INCUBATOR.

APPLICATION FILED MAY I3, 1910.

Patanted Apr. 25, 1922.

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@ALIGJMMQ UNITED STATES FRANZ BABA, OF IRVINGTON, NEW JERSEY.

INCUBATOR.

Application filed May 13,

To all whom it may concern Be it known that I, FRANZ BABA, citizen ofCzecho-Slovakia, and resident of Irvington, in the county of Essex andState of New Jersey, have invented certain new and useful Improvementsin Incubators, of which the following is a specification.

My invention relates to an incubator having an electric heating deviceand the object of the invention is to provide means to maintain thetemperature within the oven accurately at the desired degree of temperature and to attain this end with as small an amount of electric currentas possible.

For the illustration of my invention reference is had to theaccompanying drawings, in which' i Fig. l is a front view of the oven,Fig. 2 and Fig. 3 are vertical sections of Fig. 1 along the lines aa andb-b, respectively; Fig. 4 is a horizontal section through the middle ofFig. .1 along line C-C; Fig. 5 is a plan section showing the heatingelement below the floor of the oven, Fig. 6 illustrates the heatingelement behind the rear wall of the oven. Figs. 7 and 8 illustrate theheating elements behind the left and right side walls respectively, ofthe oven; Fig. 9 is a plan which illustrates in a diagrammatical way thewiring system employing several circuits; Figs. 10 and 11 show in adiagrammatical way the arrangement to stretch the wires when. expandingby heat; Fig. 12 shows the oven having a thermostat attached to keepthetemperature permanently at a certain degree of heat, and Figs. 13, 14,15, 16 and 17 show certain details of the construction of the thermostatwhich will be explained below.

Like numerals denote like parts throughout the several views, I am nowgoing to describe by way of example one apparatus embodying my inventionin which an inner boX 1, made of ceramic material, preferably porcelain,is inserted into an outer box 2 which may be of any materialconstituting a poor conductor of heat and electricity.

The cavity which naturally is left between the two boxes is closedinfront by a frame 3, the inner box 1 being closed by a door 4, the outerbox 2 by the door 5. Of the inner box 1 the bottom plate 6, thesidewalls 7 and 8 and the rear wall 9 are covered with asbestos plates10, 11, 12 and 13, respectively, wire coils 14, 15, 16 and 17 beinginterposed between the respective wall and asbestos plate.

Specification of Letters Patent.

Patented Apr. 25, 1922 1919. Serial no. 296,849.

Each of the asbestos plates, 10, 11, 12 and 13 is cut in two, thesmaller part being at tached to the bigger by means of a pair of siderails 18 and 18, made of a metal having a greater expansion coefiicientthan the metal of-which the wire coils 14, 15, 16 and 17 are made. Thewire coils are secured to the asbestos plates by means of binding posts,

for instance coil 17 to plate 13 by meansv of the posts 19 and 20. Thecoil 14 is attached to asbestos plate 10 by means of binding posts 21and 22, the short connection between them being of such thick wire thatthere is no heating effect of the electric current in this part of thecoil. The coil 15 is secured to asbestos plate 11 by means of bindingposts 23 and coil 16 to asbestos plate 12 by means of posts 24. Theelectric current is supplied from the main 25 passing through the plugsocket 26 and from there one branch 27 of the circuit passes directlyinto the coils, while the other 28 passes first through switch 29, thenthrough condenser 30 and then through regulator 81.

The Figs. 5, 6, 7, and 8 show the asbestos plates detached from eachother and unfolded; for a better understanding of the description it isassumed that the binding posts 20 and 21 are connected by wires 32 ofsuch thickness as to exclude any heating effect. Following both branches27 and 28 until one arrives at binding posts 19, one notices that thewire coil 17 provides for two parallel circuits each on each side ofasbestos plate 13 and that by means of con necting wires 32 two parallelcircuits each are provided in each half of the coil 14 on asbestos plate10. On the other side there are only two parallel circuits provided bycoil 15 and 16 on asbestos plates 11 and 12,

respectively; the wires 33 and 33 connect coil 17 with 15, wires 34:,and34 coil 15 with 16, wires 35 and 35 connect coil 16 with 17 and thuscomplete the whole wiring system.

Fig. 12 is a vertical sectional view of the oven alon the line Z)-Z) ofF i '1 corresponding to Fig. 4, but omittii the asbestos sheets and thewire coils shown in the latter figure. This Figure 12 shows the thermostatic arrangement for automatically controlling the temperature in casesame goes either beyond or below a certain degree.

To the outside of rear wall 9 a metal rod 36 it attached by means of arivet 37 (see Figs. 12,14, 15 and 16) the rod 36 closely adjoining wall9 and passing with its flat head 38 through a frame secured to the roofof base 1 by means of rivet 4.0, the upright arms -11 and 12 of frame39, holding a pin 43 on which a bifurcated metal arm 4: 1 is fuicrumed,the outer ends of which are separated from each other by means of thelink 115 made of insulating material, the outer part of arm 41 i beingfurther provided with a binding post 16 and with a point M. Thebifurcated end of arm 1 1 carries a plate 18 through which a screw 19passes to rest with its point directly upon the flat head 38. The roofof box 1 is also provided with a plate 50 secured to box 1 by means of arivet 51, the plate being titted with a binding post 52 and a metallicarm 53 ending in a point adapted to touch point 47 if arm 14: issuiliciently lowered. Socket is preferably mounted on top of the box 2receiving the current from main 9.5 (see Fig. 4) and sending branch 27of the circuit directly into coil 17 at the rear wall, the other branch28 passing through switch 29 and from there through a condenser (notshown in Fig. 12, but indicated in Fig. 9) to plate 50, arms 53 and 4-7forming part of branch 28, a wire connecting arm 4-? at binding post 46with coil 17, the arrangement of which is shown in Fig. 9 and indicatedon Fig. 12 as being located between the arrow heads of branch 27 and 28in Fig. 12. The location of metal rod 36 and the relative position ofthe walls of boxes 1 and 2, the asbestos sheet and the heating coil 16in the space between are illustrated in more detailed way by Figs. 16and 17, both figures being a horizontal section through the rear wall 9and rear wall of. box 2 at about the middle of Fig. 12.

The even is intended to be used as an incubator formedical,biological,chemical and similar scientific laboratories, as wellas for household purposes.

As source of heat only electricity is considered and in connectionherewith an important feature is immediately obvious from an inspectionof the drawings for contrary to the usual way of mounting the wire overall the surface of the heating chamber only part of the outside surfaceof the chamber is covered with wire in my invention and certain zonesare entirely withheld from the direct action of the electric current.The arrangement of the resistance wire around the outside of box 1 ismade that there are free zones uncovered with wire; for instance thecoil L1 below box 1 leaves of the space, in the rear, entirely uncoveredwith wire and provides same only for J, of the space at the right andleft, so that of the middle is not covered with wires either.

The sides are covered with wire only to of their height, measured fromthe bottom to the top, and of the width measured from the front, so thatof the space at the top and at the rear are not covered with wire.

The rear is covered with wire to only Z,- of its width and to of itsheight. In the middle there is a space left free from top to bottom, thespace being approximately 5,} inch wide to receive the metal rod 36.

The top or roof of base 1 is not covered with any wiring at all, asmaterial for the box 1 porcelain is preferred though any other ceramicor similar material may be applied, the surfaces of box 1, at leastinside, being glazed, the wire can therefore be applied directly uponthe outside wall of the box 1, an asbestos layer being put on topreserve the heat and concentrate same upon box 1.

The coils of resistance wire are prefer: bly as described in thispresent application, mounted on asbestos plates to be easily removed andput back again in case any of the coils fails to work for some cause orother. The interstice between coil and outer box 2 is either maintainedas an air space acting as an insulator (a certain circulation takingplace through holes in the bottom and top of box 2)or the interstice isfilled up with a poor heat conductor, for instance with material likeasbestos, glasswool, etc. The box 2 can be made from porcelain,asbestos, metal or wood, the material depending very much upon thedegree of heat for which the oven is intended. The coils can be mountedthat a plurality of circuits may be applied, two circuits being shown byway of example in the drawings; according to the desired temperatureeither one or more circuits are switched in.

The regulation of the heat of the oven is operated by means of athermostat, metal rod 36 and the arm 1 1 mounted upon the roof of box 1being parts of this particular outfit.

This new arrangement of the coils admits of an alisolutely eventemperature within the inner sp cc of box 1 and offers the furtheradvai'itage that the objects to be treated. within box 1 can never comeinto contact with the coils whereby a short circuit within the coilsbecomes a very remote possibility. The coil 14; reaches its current fromcoil 17, the binding posts 20 and 21 being actually united in the ovenand the short connecting wires 32 between Figs. (3 and are only insertedfor an easier understanding of the: description.

A. porcelain box to serve as box 1 is of particular advantage because itcan easily be cleaned inside with warm water, or can be disinfected inany desired way because the coils are adjoining the. outside walls ofbox 1. As the inside box 1 of porcelain. also admits of treatingmaterials of acid reaction the door 41 closing box 1, can then also bemade of porcelain and can be titted as to have only porcelain partstouch each other,

all metal parts being then avoided inside box 1, the various-rivetsmentioned above being for instance substituted by countersunk screwresting in a recess of the outside wall or box '1. As porcelain is apoor heat conductor and the coils of resistance wire closely adjoin box1, a heat regulator of the type measuring and depending upon thetemperature inside box 1 would not be of advantage, for the porcelainbox 1 heats up slowly and before the heat would penetrate the walls ofbox 1 to reach the regulator inside of same, the temperature at; theinside walls of box 1 would be higher than desired before the insideregulator would switch oil the current; a further consequence would bethat the temperatureeven after switching oli the current would stillrise owing to the radiation of heat from the porcelain walls and if thenthe temperature sinks'again to the desired degree When the regulator isexpected to automatically switch in again the electric current, then thetemperature at the outside walls has fallen considerably lower thandesirable. My invention has the purpose to attain an even heat withinbox 1 by means of arranging the wire coils as de scribed whereby thepoor heat conductivity of the porcelainis turned to good advantage asthe heat spreads more evenly already within and at the walls of thereceiving box 1. My invention has the further purpose to provide theoven with a' most sensitive regulator which guarantees already by itsclose attachment to the porcelain box, having a small co-etficient ofexpansion, and by its own considerably greater .coeflicient orexpansion, a quick and reliable eii'ect and thereby quick disconnectionsor connections of the circuit with the heating coils.

The metal rod 36, being the essential part of the thermostat, is closelyjoined to the wall of box 1 and receives its heat from said wall, theclosely adjoining coils being covered with asbestos (see Fig. 16) toavoid the influencing of the accuracy 01 the regulator by heat radiatingfrom the coils; the

metal rod 36 receiving heat from box 1, the rod will react upon theheating eilect in short intervals and as thus the heat o1 the porcelainbox 1 is constantly measured or regulated, respectively, it stands toreason that the temperature inside the oven will soon be constant.Within the bifurcated arm 44 the set screw 49 serves automatically tomaintain the desired temperature after same is reached once, all one hasto do is to turn the screw until its lowest point reaches the flat head38 of metalrod 36, which by the way is made of the expansionof' rod 86,the joint of points 47 and 5 1 is interrupted because rod 36 lifts screw49 and armlt united therewith. Upon the slightest cooling off of rod 36the electric circuit is reestablished because then brass upon' thearrangement shown in Figs. 10 and 11 where it is shown that to theasbestos sheet by binding posts 19 and slung around or through loops 56.Upon expansion of the wires, they hang loose and might admit of a shortcircuit, which is, l1OW8V61', aVOlCl6Cl as" the metal rails 18 and '18have a greater coefficient of expansion than the wires and whenexpansion takes place owing to an increase in temperature, the railsexpand more than the wires and thus keep the latter always straightenedor the two parts of the asbestos plate are kept apart by springs 55whereby the wires are also kept straight notwithstanding expansion owingto heat.

the wires are joined The operation of my ovenisabout as be sufficientthe operator connects the upper terminal of branch circuit 27 withbinding post 19 plus and the lower terminal of branch circuit 28 withbinding post 19 (see Fig. 9) whereupon the other binding post 19 plus isconnected by wire 33 to binding post 23 plus then by joining the outerbranch of coil 15, the other end binding post 23 plus by means ofwire 34to binding post 24-, thereby establishing connection with the innerbranch of coil 16. The other end of coil 16 is joined to coil 17 bymeans of wire 85 at binding posts 24 and 19. As soon as the desiredtemperature is reached the set screw 49 is turned down until its lowerend reaches flat head 38 of rod 36. If the temperature goes beyond thedesired degree rod 36 will receive more heat from wall 9 and willexpandsoas to lift arm 14 whereby the contact between points 54 and 47will be interrupted and the flow of the electric current will cease asis obvious from a'study of Fig. 12. As soon as rod 36. has cooled downagain to the proper temperature it will assume its original length againand naturally arm' l l will also sink into its original position thusre-establishing contact between points 53 and 47 whereupon the electriccurrent will continue to flow and to exert its heating effect. It isobvious that thereby the walls of box 1 are continuously kept at thesame temperature and that owing to the radiation of heat from the wallstowards the center of box 1 the temperature must uniformly increase atall points of the chamber towards the desired degree and that there canbe no variations after this degree is once obtained. Screw 49 could. beprovided with a kind of a scale at its head which would indicate to theoperator how far he has to turn down said screw to obtain any of thevarious temperatures he wants to obtain; likewise stem 53 could bearranged to have the form of a tube within which point 5a can slide upand down and a scale on this modified stem would accomplish the sameresult in regard to anticipating the effect of the thermostaticregulator.

What I claim is:

1. An incubator for producing a constant and'uniform temperature,comprising an inner box of material of low heat conductivity and beingan insulator for electricity, an outer box surrounding said inner boxand including an air space between both boxes, a system of resistancewires located within said air space and applied directly upon theoutside of parts only of the bottom, sidewalls and rear side of saidinner box, plates of low heat conductivity and being insulators forelectricity covering said system of resistance wires, connections topass the electric current through the system of resistance wires, and athermostatic regulator controlling the flow of electric current, havingits actuating members secured directly to the outside wall of the innerbox.

2. An incubator for producing a constant and uniform temperature,comprising an inner box made of material of low heat conductivity andbeing an insulator for electricity, an outer box surrounding said innerbox and inclosing an air space between both boxes, plates of low heatconductivity and being insulators for electricity covering the bottom,side walls and rear side of said inner box, a system of resistance wiresmounted upon aforesaid plates being insulators for both heat andelectricity and be ing adapted to extend in. length in proportion. tothe extension of the coils of resistance wires caused by the flow of theelectric current through them.

3. In an incubator of the character as described, the combination ofinsulating plates for both heat and electricity, said plates beingdivided in. two and held at their edges by metal rails having a greaterexpansion coel'licient than the metal from which the coils of resistancewires are made so as to stretch the latter when heated.

4. An incubator for producing a constant and uniform temperature,comprising an inner box of material of low heat conductivity and beingan insulator for electricity, preferably porcelain, an outer boxsurrounding said inner box and inclosing an air space between saidboxes, a system of resistance wires located within said air space andapplied directly upon the outside wall of the inner box connections topass the electric current through the system of resistance wires, ametallic element, capable of expanding and contracting owing to changesof temperature, secured to and heated by the outside wall of the innerbox and adapted to interrupt and reestablish the flow of the electriccurrent through the resistance wires.

5. An incubator for producing a constant and uniform temperaturecomprising an. inner box of material of low heat conductivity and beingan insulator for electricity, preterably porcelain, an outer box of heatinsulating material surrounding said inner box and inclosing an airspace between said boxes, plates of heat insulating material coveringthe bottom and the sidewalls of the inner box removably arranged withinsaid air space, a system of resistance wires mounted upon aforesaid heatinsulating plates and held by same unto parts of the bottom and thesidewalls leaving certain zones of their surface and the top wallentirely free of such resistance wires, connections to pass the electriccurrent through the system of resistance wires admitting of a pluralityof circuits, a metallic element, capable of expanding and contractingowing to changes of temperature, secured to and heated by the outsidewall of the inner box and adapted to interrupt and reestablish the flowof the electric current through the resistance Wires.

6. In an incubator of the character described, a metallic actuatingmember forming a part of the thermostatic regulator being secured to theoutside of theinner box, the walls of said inner box being made of insulating material for both heat aud e]cctri ity secured to the outsidewall of the box to be heated.

7. In the operation of an incubator as det-zcribed, the step ofregulating the heat of the incubator by communicating the heat Off thewalls made of material acting as an insulater for both heat andelectricity, of the inner box to a metallic element secured to theoutside wall of aforesaid inner box and adapted to actuate the otherparts of the thermostatic regulator controlling the flow of the electricheating current.

Signed at Newark, in the county of Essex and State of New Jersey, this10 day of May, A. D. 1919.

FRANZ BABA.

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